Method of treating milk



' Patented (UNITED STATES mans 7 2,110,115 7 METHOD or rename MILKEdward W. Smith, Melrose, Mass assignor to Submarine Signal Company,Boston, Mass., a'

corporation of Maine No Drawing.

Application April 2, 1937,

. Serial No. 134,575

7 Claims.

The present invention relates to a method of treating milk and moreparticularly to a method of producing soft-curd milk.

I It is an object of the present invention to pro- 1 5 vide a moreconvenient and economical method of producing soft-curdmilk than methodsheretofore used. A further object of the present invention is'to makeavailable a soft-curd milk having a standard butter-fat content and ofsuch properties that the depth of the cream which rises to the top ofthe milk on standing zzvliilllk be substantially the same as withuntreated A number of methodshave heretofore been proposed for thetreatment of milk to reduce the curd tension thereof. Some of theseprocesses consist in dispersing the butter fat in small particlesthroughout the body of the milk, that is in homogenizing the milk. Suchhomogenization may be obtained by the use of the well-known pressurehomogenizer. It may also be obtained by subjecting the milk to theaction of intense compressional wave energy as set forth in thecopending application of Leslie A. Chambers.

Serial No. 756,504, filed December 4, 1934.

The above processes result in a uniform dispersion of the butter fatthroughout the body of the milk. If such milk is allowed to stand,substantially no cream will rise to the top as with untreated milk. Itis oftentimes convenient,

however, to be able to remove readily the cream from the m-i1k.- Forexample, for infant feeding soft-curd milk is desired because it iseasily digested, but not all infants can readily digest 35, muchbutter-fat. For this reason it is highly desirable to have available amilk which has a low curd tension, but yet upon which the cream willrise upon standing. In my copending application Serial No. 14,643, filedApril 4, 1935, I have described a method 1 whereby such a milk productcould be obtained. The method .set forth in that application wasbased-upon my discovery that iii-reducing the curd tension of milk byhomogenization it is only necessary to disperse substantially one-halfof one percent by weight of butter fat within the body oi the milk. Inthat application the majority of the creamwas initially removed from thewhole milk, leaving only about one-halt'of one percent butter fatbyweight within the milk; the milk with this small quantity of cream washomogenized and subsequently the cream which '*'was initially removedwas added to the treated milk I have now discovered that a milk product.

I having a sumciently low curd tension to bring it within the classusually termed as soft-curd milk (present New York city standard, 33grams or below) can be obtained by a simple and convenient procedure.Furthermore, soft-curd milk having a cream line substantially the sameas normal untreated milk is also readily obtained.

According to the present invention whole milkwhich may have a curdtension of 40 grams or more is treated by any desired method to reduceits curd tension to approximately 20 grams or less. This treated milk isthen mixed with untreated milk in the ratioof one part of 'the treatedmilk to ford parts of the untreated milk by volume. By thus mixing milkwhich has been treated to have a low curd tension with normal untreatedmilk having a higher curd tension, the curd tension of the entire bodyof the milk can be reduced suflicientlyso that it is still below thestandard generally accepted for soft-curd milk.

For example, I have taken normal wholemarket milk having a curd tensionof approximately 40 grams and mixed four parts by volume of this milkwith one part of slmflar milk which was treated by homogenimtion toreduce its curd tension to approximately 19 grams and have obtained aresulting milk whose curd tension is about 28 grams, which is well belowthe New York city standard of 33 grams for soft-curd milk. Furthermore,the resulting milk product has the much desired characteristic that itscream content will, when the milk is allowed to stand, rise to the topof the milk to give a cream line of substantially the same depth as thatof the milk before treatment.

If the ratio of treated to untreated milk is made somewhat less than oneto four, the resultant product will have a curd tension substantiallynearer to the initial curd tension of the treated portion of the milk,whereas if the ratio of treated to untreated milk is made greater thanone to four, the curd tension of the resultant mixture will tend toapproach that of the untreated milk.

Heretofore it had been supposed that it was necessary in order to obtaina reductio'n in curd tension of milk by-homogenization to disperse atleast a small amount of butter fat within the entire body of the milkwhose curd tension was to be reduced. It will appear from the above,however, that by the present invention it is now merely necessary todisperse the desired amount of butter fat within a relatively smallquantity of milk and subsequently to add thereto a quantity of untreatedmilk in order to reduce the curd tension of the entire body of the milk.In order to obtain a substantial reduction in curd tension it appears tobe sumcient if the quantity of the dispersed butter fat is at leastapproximately one-half of one percent by weight of the total final bodyof the milk.

' Having now described my invention, I claim:

1. A method of treating normal whole hard curd milk which compriseshomogenizing oneflfth of the body of the milk to reduce the curd tensionthereof to a relatively low value and' remixing the same after treatmentwith the remainder of the milk, whereby the mixture becomes a soft curdmilk. 1

2. A method of treating milk which comprises dispersing the butter fatin a-quantity ofhard curd milk to reduce the curd tension to arelatively low value and subsequently adding a minor quantity of thetreated milk to a major quantity of hard curd milk, whereby-the curdtension ofthe mixture is reduced to a soft curd value.

3. A method of treating, normal whole hard curd milk which compriseshomogenizing a minor ture becomes a soft curd milk; 7

4. A method of treating normal whole hard I curd milk to reduce the'curdtension thereof to a soft curd value which comprises homogenizing aportion of the same to reduce the curd tension of that portion to arelatively low value and subsequently mixing the treated portion withsuch quantity of untreated portion that the butter fat content of thetreated portion is approximately one-half of one percent by weight ofthe total final body of the milk.

5. A method of treating normal whole hard curd milk to reduce the curdtension thereof to a soft curd value which comprises homogenizing aportion of the same to reduce the curd tension of that portion to arelatively low value and subsequently mixing the treated portion with aquantity of the untreated portion in such proportions that the cream ofthe combined milk when it rises to the surface appears to haveapproximately the same volume as the cream in the original whole milk.

6. A method of treating milk which comprises homogenizing a quantity ofnormal whole hard "curd milk to reduce the curd tension thereof to arelatively low value and subsequently mixing the same with a quantity ofsimilar whole hard curd milk which has not been homogenized inproportion approximately of one part of the former to four parts of thelatter, whereby a soft curd milk is produced.

7. A method of making soft curd milk which comprises homogenizing aminor body of hard curd milk to reduce the curd tension thereof to arelatively low value and subsequently mixing said body of milk with amajor body of hard curd milk whereby the curd tension of the mixture isbelow the maximum limits established for soft curd milk.

' EDWARD W. SMITH.

